Snow shovels existed since the first time people have had to move snow. The most popular styles of snow shovels were derived from grain shovels. They have large, rectangular, flat blades and a handle. They are designed to lift snow to remove it. In most cases they do a reasonable but laborious job of cleaning snow. Using standard shovels to clear roofs, however, is problematic. First, the roofing material may be damaged as the blade of a snow shovel is pushed down into the snow. Picking up and disposing snow is also difficult as there is a chance of falling from the roof. More modern shovels have been developed for cleaning that are basically scoops. These scoops are not lifted but pushed along. Although they are an improvement over the standard shovels, they still have problems with dumping snow and, like shovels, they have limited capacity to move large quantities of snow at a time.
Several devices have been developed to aid in removal of snow from roofs. Unlike shovels, these devices are used to move snow without lifting it or having to dump snow over the edge of a roof that could cause a fall. These devices fall into two groups. Examples of the first group are U.S. Pat. Nos. 3,483,643, 4,024,654, 2,603,892, 4,185,403, and 4,249,767. U.S. Pat. No. 3,483,643 is called a snow scraper. It has a flat blade that is hinged on a forked frame. A handle is attached to the frame. The device is slid upwards over snow on a roof. As it is pushed upwards, the blade lies flat on the surface of the snow. When the desired height on the roof is reached, the handle is pulled. This causes the blade to become stuck in the snow. Continued pulling forces the blade to open and extend perpendicular to the handle. At this point, any snow behind the blade will be pulled off the roof. This device has two main problems. First, if the user is trying to pull a lot of snow from the roof, the user needs a lot of strength to force the blade through the snow. Second, any snow that does come off of the roof falls on the user, perhaps causing injury. U.S. Pat. No. 4,024,654 is a cylindrical device that dragged over a roof from the ground. The same difficulties apply here. Wet, heavy snow or snow that has frozen to the roof cannot be pulled easily from the roof. Moreover, any snow that is pulled from the roof falls on the user if the user is not careful. The remainder of the patents in this group are similar to the first set. The user typically pulls snow from the roof by standing below the roof. U.S. Pat. No. 2,603,892, in a rather unusual design uses a rake like device that is operated from inside a building through a window. Although this device eliminates the possibility of being hit with the falling snow, it is a cumbersome device that appears limited in its range of operation.
Examples of the second group of devices are found in U.S. Pat. Nos. 3,998,486 and 5,083,388. U.S. Pat. No. 3,998,486 shows a device with a rectangular frame and wheels. A handle is attached at the top of this frame. A long sheet of plastic is attached to the lower portion of the frame, located between the wheels. U.S. Pat. No. 5,083,388 has a frame with two vertical portions and a lower portion connecting the vertical members. A roll of plastic sheeting is attached to the lower frame member. A handle is attached to the center of the top of the lower frame portion. Both devices are used in a similar manner. The frame is either pushed or pulled along a roof. The frame dislodges quantities of snow, which then contact the plastic sheeting. The sheeting is designed to extend downward, below the eves. When the snow hits the sheeting, the plastic's low coefficient of friction causes the snow to quickly slide down the plastic sheet off the roof. U.S. Pat. No. 5,083,388 has the ability to roll up the sheeting after use for storage. Although these designs are a significant improvement over the latter designs, the frames are not large enough for efficient snow removal. They are designed to be light weight, their size makes them difficult to move through deep snow without considerable effort. The frame of U.S. Pat. No. 3,998,486, for example, is tubular, which does not easily cut through hard packed snow. Similarly, even though the sides of U.S. Pat. No. 5,083,388 are thin which helps them cut through hard snow, the center member that carries the tarp roll hinders the snow removal. Moreover, in both designs, the handle is mounted too low for practical and efficient use. Such a low handle position causes the user to lean forward when pulling the device up a roof. The handle position also makes it difficult to operate the devices from the ground because of the pitch of the roof. Only by adding extra length to the handles can a good attack angle be achieved. It is possible that 30 to 50 feet of handle would have to be used to reach the full extent of certain roofs. Such a handle length is totally impractical. Thus, pulling either of these devices through hard packed snow is difficult and pushing them from the ground is equally impractical.